Lewis l



L.L"."TA.TUM. MOTOR DRn/EN GQMPRESSOH. APPLICATION 'FILED Nby. 1B. 1915.

Putentedept. 9, 1919.

MABB..

LEWIS L. TATUM, 0F MILWAUKEE, WISCONSIN, ALSSIGNOR T0 THE C'U'TLER-I-IAllvIlllIiElI MFG. CCL, 0F MILWAUKEE, WISCONSIN, A CORPORATION 0F WISCONSIN.

- MOTOReDRIVEN COMIRESSOR.

\ storage tank pressure and more particularly lili to control means for the compressor motor to automatically start'and stop thesame under given storage tank pressures. Unloaders of the character specified hav been found very advantageous in themselves, but use thereof has given rise to diliculties in controlling the .compressor motor by the customary pressure responsive means. For

example, Where such an unloader and control means are employed the latter beingr directly subjected to the pressure of the storage tank, 'd-illiculty' has been-experienced through response of the control means prior to response of ythe unloader,.or response of the unloader rior to response of the control meansl n the former instance, the unloader is rendered ineffective so that the compressor motor must restart under full load, while in the latter instance response of the unloader so reduces the pressure in the storage tank as to render the switch unresponsive to stop the compressor motor. Various compressor systems, such as those including electrically operated unloaders, have been proposed to overcome the didiculties mentioned but it Vis understood that the only successful systems are of an elaborate and costly character. The presentv invention-llas among its objects to so assrnliate the pressure control means Iwith the storage tanlc 'and unloader as to enable entirely satisfactory use of an unloader of the typer mentioned and in fact practically any species of such type.

A further'object is to so incorporate th pressure ,control means in the compressor system as to render response thereof to stop the compressor motor dependent upon response of the unloader valve and as to insure its release to restart the compressor motor prior to closure ot t if i l i valve,

specification of Letters raient.

Patented Sept, tl, ltllll'.

application ala november 1s, 191s. serial no. iaacea.

Various other objects and advantages el the invention will hereinafter a pear.

The accompanying drawing scliematically illustrates one embodiment of the invention which .will now be described, it being understood that4 the embodiment illustrated is susceptible of various modifications falling,Y within the scope of the appended claims.

Referring to the drawing, there is illustrated a compressor lidriven 1by a motor 2 'f throughthe usual driving connections vto supply air to a storage tank 3 through check valves 4 and pipe 5. The compressor is provided with intalce valves 6 and 7 respectively providedwith pistons 8 and 9 tting cylinders 10 and 11 respectively, bot cylinders being connected through a pipe l2' to an unloader valve 13, This valve is oi a Awell known type comprising a casing having a partition le and piston 15 reciprocable Within said casing and provided with a needle valve 16 ,controlling an opening in said partition. The section of the casing below the partition is connected to pipe 12 and has a iloleeder port 17 while the section of the casing above the partition is connected 'by -pipes 5 and l5 to the storage tank 3. Thus the lower side of thepiston of the unloader valve is subjected to the pressure of the storagetank, while an opposing helical spring 18 is interposed between said piston and an end cap 19 'of the valve easing. The spring 18 thus serves to regulate the action of the unloader valve, saidY spring being variable in its action by threaded adjustment of the cap 19 on the easing,

The above described system is of a well known type and as will be understood the uploader valve will respond at a predetermined maximum storage tank pressure to 'open theuneedle valve andv thus admit'air storage tank-pressure decreases to a predeteminedvalueto release the unloader valve the bleeder port will `permit the air to gradually escape from the cylinders 10 and lili' ll therebypermittingE the intake valves to reclose to 'load the meter. v

Considering now tl1e"eont1ol means for the motor, the same is shvn as comprising to the fulcrum point of said pivoted contact to operate the latter in reverse directions with a snap action. The arm 23 1s biased by a .spring 25 1n a direction to engage contact 22 with contact.

2l and is operatively connected to a dia-` phragm 2G to be moved 1n reverse direction to disengage said contacts underv given pressure. conditions, said diaphragm having its casing connected by a pipe 27 to pipe l2. Thus the switch 1s connected to the storage tank through Ithe unloader valve and inv consequence 'will respond only -When the unloader is 'rendered effective.

Hence assuming adjustment of the'pres sure switch 'for response at substantially theJ same pressure value as the unloader valve it will respond immediately upon response ot' the latter and in so doing will break the compressor motor circuit. Then through leakage and use oit'l the storage tank air the pressure in the piping system of the unloader will gradually decreasefand assu1ning the adj ust-ment of the pressure valve to release at a pressure value slightly higher than at which the unloader valve closes, the motor will be insured restaiting while the intake valves are still retained in open position. irc iordingly the unloader and the pressure control switch will cooperate to insure the desired conditionsA in stopping and restarting of the controlled motor.

What I claim as new and desire to secure by Letters Patent is:

l. 1n con'ibination, a motor driven compressor, a storage tank supplied thereby, a.

starting;4 and stopping' device for Said compressor, an unloader valve for said compressor. means for subjecting one ot'said lasttwo mentioned elements to control by the pressure within said tank and means coordinating said elements for control one by the other for unloadinjr said compressor when stopped and for restarting operation .of said device prior to return of said unloader valvel ln combination, a motor driven. compressor, a storage tank supplied thereby, compressor unloading; means including an unloader valve directly responsive to storage tank pressure and control means for t-he compressor motor responsive to storage tank pressure but subject t0 control by said unloader valve, said control means being biased to return to normal 'position at. a pressurevalue exceeding that at which said Valve recloses.

3. In combination, a motor driven compresser, a storage tank supplied thereby, a

age tank pressure and a chamber to be subjected to and relieved of such pressure by said valve and pressure responsive means subjected to the pressure of said chamber t-o start and stop the compressor motor, said control means being biased to return to normal position at a pressure value insuring continued unloader pressure' for a subsequent temporary period.

5. In combination, a motor driven eom pressoir having a valve to permit the saine to discharge to the atmosphere, said valve having means responsive to fluid pressure to hold said valve open, a storage tank connected to said compressor, a supply connection between said valve operating nieans and said storage tank including an unloader valve directly responsive to the storage tank pressure and having a bleedenopening, and a starting and stopping switch for the compressor motor responsive to fluid pressure and connected to said storage tank through said unloader valve, said switch being biased to return to normal position at a pressure exceeding that at which said valve recloses.

In witness whereof, I have hereunto subscribed my name.

LEVVTS L. TATM. 

